I've used WAL-E (the predecessor of this) for backing up Postgres's DB for years and it's been a very pleasant experience. From what I've read so far this looks like it's superior in every way. Lower resource usage, faster operation, and the switch to Go for WAL-G (v.s. Python for WAL-E) means no more mucking with Python versions either.
Great job to everybody that's working on this. I'm looking forward to trying it out.